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E. E. BROSTROM. METHOD'OF MEASURiNG CONCEALED OBJECTS.

APPLICATION F [LED JAN. 171'1920- Patented Nov, 15, 1921.

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METHOD OF MEASURING CONCEALED OBJECTS.

Specification of Letters Patent.

Application filed lfanuary 17, 1920. Serial No. 353,360.

To all whom it may concern Be it known that I, EDWARD E. BROSTROM,

' a citizen of the United States, residing at Los Angeles, county of LosAngeles, and State of California, have invented a certain new and usefulMethod of MeasuringCon cealed Objects, of which the following is aspecification.

This invention relates to a means for measuring objects or spaces hiddenfrom View or contained in' opat ue substances or materials, and it hasespecial reference to a method of determining with precision thedimensions of bodies'thus concealed in a mass or masses of materialimpervious to light, an object of the invention being to provide asimple, efficient and accurate method of measurement of concealedobjects, spaces or structure from an image or record of the same made ona negative plate or film.

The accompanying drawing is illustrative of the application of themethod in'one field, to wit, osteological science, where, for instance,the ascertainment of the dimensions of the inlet and outlet of thefemale bony pelvis will in advance determine conditions liable or apt todevelop and be met with during pregnancy and labor, and prior, and whichwill guide a physician in the care and treatment of a patient and in hisdetermination of the tLII'ltIOII,

The figure is a schematic view, showing a possibility of par- ,bonypelvis, a plate upon which the image thereof is to be recorded, and thesource of penetrative ray. i I In general, the invention involves theaccurate and true calculation of dimensional areas of concealed objects,bodies or structures by making an'X-ray picture of the object to bemeasured and of unknown dimensions, in association or combination withan object or objects of predetermined. or known dimensions used as acoetlicient, and specifically the invention comprises the placement ordisposition of a body or association of bodies or objects of calculatedand known dimensions, distance or separation, on a plane parallelwitlithe object, body or structure of unknown dimensions, and in closeassociationwith or proximity to said body,-.but which bod-y, forinstance in medical work, may be located and certain landmarksthereofestablished. The objects or elements of known dimension maycomprise acuininate members or very fine points, which may be sodisposed and supported that only the extreme ends lie within the focalplane of the primary Roentgen ray.

Herein the term, inlet refers to the brim of the true pelvis, alsodesignated the superior strait; it is also designated the an atomicalinlet, of the true pelvis, as dissubstance permeable to light andrepresent units of measurement, for which purpose the opaque bodies orelements 3 are determinately spaced,

These opaque bodies or elements are re corded upon the photographicplate with the object photographed. It is reopuired that the plate orfilm 4;, be parallel to the plane of the concealed object to becalculated and pictured and Within the penetration area of the rays andthat the rays 5 of the Roentgen projector 6 be at right angles to boththe object 1 and the plate 4t, which obviously must be centrallylocated.

Theimprint of the object 1, and modulus 3,

show the ratio of enlargement oi? the object.

and the spaces between the elements of the modulus to be the same.Therefore the accurate measurement of the pelvic inlet or outlet isobtained in the tollowing manner.

To the physician the ascertainment oi. the measurements of those axesintowhich. a human pelvis is divided is of the greatest importance andthese axes comprise the following, to-wit: the conjugatc aicis orconjugate, which refers to an imaginary line extending from the tip ofthe sacral promontary to the middle aiid .top of the pubyc symphisis;the transverse axis, which refers to animaginary line across thegreatest di- Patented Nov. 15,1921,

ameter oil? the inlet; and the oblique axes,

which refers to imaginarv lines diverging from the sacro-lliacarticulation to the lleo' pectineal eminence of the inlet. The obliquelandmarks of the pelvis, as appearingupon the plate.-

The resultingmeasui ements, that is, in

the accompanying illustration, those most.

necessary. to the obstetrical branch of asteology, namely the conjugate,transverse and loblique axes or diameters of the pelvic inlet,

etc, are then each divided by the distance, in millimeters, representedby the spaces between the opaque bodies in the modulus, then multipliedby the dimension of the known object and the result will be the correctmeasurement; for instance:

Say the transverse axis of the enlarged picture orimagc measures 12centimeters; the oblique axis, 12 centimeters, and the conjugate axis,11.8 centimeters The markings or spacings on the modulus represent 25.4millimeters, or exactly one inch apart. Upon this enlarged image, thedistance between the markings of the modulus is 28 millimeters. Themodulus on the photographic plate being enlarged in the same ratio asthe object photographed, the true measurement of the photographed abjectis arrived at by dividing 28' millimetersinto 118 millimeters equals4.21 times. 4.21 times 25.4, (actual size of coeflicient in 1millimeters), equals 106.9 millimeters which on being reducedt-ocentimeters equals 10.69 centimeters. (A small traction is discarded inthe product of 28 into 118.)

2. Dividing 28 millimeters into 120 millimeters. equals 4:28\times. 28times (actual size of coeilicient in millimeters); equals 108.7millimeters, which on being reduced -to centimeters, equals 10.87cent-imeters. (A small fracti'on is discarded in the product of 28 into120.) a

3. Same as foregoing.

The measurements obtained by this method are accurate measurements ofthe concealed object, space or structure brought to light upon anegative or photographic plate and obviously, the pre(letern'iination ofthe actual measurement or dimension of a bony structure willindicatewhether normal processes of nature are-possible and the stepsnecessary if abnormality exists.

What I claim, is:

The method of measuring concealed objects or spaces, consisting indisposing the object of unknown dimension in -a plane parallel to thesensitive plate, the object to be measured and the plate being at rightangles to the general, diretion of rays issuing from a predeterminedcommon point, setting an object of known dimensions in the same plane asthe object of unknown dimensions, making the exposureby means of actinicrays issuing from said point, measuring the distances desired on thenegative,. dividing such measurements by the dimension of the image onthe negative of the object of known dimension, and finally multiplyingthe result by the dimension of the known object.

In testimon whereof I haye set my hand. E WARD E. B'ROSTROM.

